Guide rail structure for lift platform



Jan. 31, 196i E. WOLDRING GUIDE RAIL STRUCTURE FORLIFT PLATFO FiledApril 18, 1958 2 Sheets-Sheet 1 INVENTQR.

BY WM A7TORA/EYS Jan. 31, 1961 E. woLDRlNG GUIDI: RAIL STRUCTURE FURLIFT PLATFORM 2 Sheets-Sheet 2 Filed April 18, 1958 TUT INVENTOR. 7 cr//o/o/r//y BY /0 f @m 7M 2,? ld Patented Jan.. 3i, llSl GUIDE RARSTRUCTURE FOR LIFT PLATFRM Egbert Woldring, Grand Rapids, Mich.,assignor to The Rapids-Standard Company, Inc., Grand Rapids, Mich., acorporation of Michigan Filed Apr. 18, 1953, Ser. No. 729,412'

1 Claim. (Ci. 30S- 6) This invention relates to lift platforms ingeneral, and more particularly to means for guiding lift platforms inthe course of their vertical movement.

Most lift platforms are provided with guide wheels which are mounted onthe sides of the liftv platform itself. These guide wheels usuallycooperate with stationary vertical tracks or guide rails. The wheels onthe lift pltaform are mounted near the side ends of the platform membersand usually near the top and bottom limits of the lift carriage member.

Such guide mounting of lift carriages causes the full load of the liftplatform to be concentrated on the guide wheels and, through them, onthe guide rails where engaged by the guide wheels. Accordingly, theguide rails are required to be of heavy, durable, constructionthroughout their length and the guide wheel construction must also beexceptionally serviceable because of the load concentration thereon.Such factors increase costs of manufacturing, maintenance, and repair.

As a rule, the guide wheels and rails are required to be protected orshielded from possible damage. Any damage or interference with thefunction of either the guide wheels or guide rails will disrupt theoperation of the lift carriage member. Each of the guide wheels must befreely rotatable at all times and any misalignment relative to the guiderails may prove quite serious.

Any eccentric loading of the lift platform, towards one end thereof,produces a binding end thrust on the guide wheels of most liftcarriages. Such loading must be taken by the guide flanges of the guidewheels. This is another reason that the guide wheels are required to beof a massive and durable construction. Obviously, such ange loading ofthe guide wheels is most undesirable. However, thus far all means whichhave been proposed to relieve this situation have proven generallyunsatisfactory. Such means have included a double set of guide wheelsprovided on the guide carriage, or equally expensive and impracticalconstruction.

it is an object of this invention to teach a new and improved guidestructure for lift platforms. Such guide structure includes having aplurality of rotatable guide wheels mounted on a stationary guide memberand eliminates having guide wheels provided on the carriage member.

Itis an object of this invention to disclose a guide rail structure forlift platforms that is highly serviceable and which has numerousadvantages over previously known guide rail structures for liftplatforms. The use of a multiplicity of guide wheels mounted on astationary guide rail does not require that the guide wheels becontinuously in service. Further, when they are in service thefrictional load thereon is divided between numerous of them. Accordinglythe guide wheels can be of lighter construction which is far lessexpensive to make.

Another object of this invention is to teach the use of standardlyavailable guide Wheel construction for use with lift platforms. Theguide rail structure of this invention makes use of commonly knownconveyor wheeled track sections. Such track sections are mounted withina channel guide for wheel engagement with a guide flange of the liftplatform. f v

The conveyor wheel track sections are relatively inexpensive because ofthe standardized mass production methods used in their manufacture. Thetrack sections and the wheels of such track sections are readilyreplaced if damaged. `However, in view of the use of multiple wheels,the chance of wheel damage is minimal. Further, damage of one wheel willnot interfere with the operation of the lift carriage which is guidedthereby.

The conveyor wheel guide rails ofthe disclosed guide' rail structure arearranged for radial loading and are free'A of any thrust loading due tooff center loading of the lift platform or otherwise. The lift carriageincludes a simple guide tlange which is engaged on opposite sides and onits end face by the multiple wheels of the guide means. TheV side wallengaging wheels are required to take no end thrust loading. The end wallengaging wheels, on the other hand, are disposed to take such forcesradially.

A further object and advantage in the practice of thisy invention is tosimplify the construction of the lift plattrackr sections is commonlyusable as a structural mem-v ber in forming the lift platform andelsewhere. Conse-V quently, such members may be kept in stock fornumerous diiferent purposes and will be available to extend,

revise, repair or otherwise change the guide rail struc-v ture disclosedherein. Such track sections are readily adapted to include the yconveyorwheels when and where required. Thus the track Vsections may be cut tolength, as required, and be adapted to include conveyor wheels, asdesired, right on the erection site.

These and other objects and advantages will be more apparent in theillustration and description of a working embodiment of this invention,as hereinafter set forth.

In the drawings:

Fig. l is a front view of a lift platform and guide rail structure.

Fig. 2 is a side view of the same lift platform and guide railstructure.

Fig. 3 is a cross sectional and enlarged view through one of the guiderails of the structure shown by Figs. 1 and 2.

Fig. 4 is a perspective view of a part of the guide rail structure ofthis invention.

The lift platform and guide rail structure shown in the drawings, andlater described in further detail, includes a housing of a semi-portablenature having a lift platform exposed on one side thereof. The housinghas structural guide rails framing its open side and which are adaptedto receive and guide the lift platform in the course of its verticaltravel. by an endless drive chain and chain drive mechanism mounted inthe housing member.

Referring to the drawings; the housing l2 is formed as a shield orshroud which has a back wall 14 and side walls 16 and 18. A cover plate20 closes the top of the housing 12. A pair of stabilizing legs 22 aresecured near the bottom front face of the housing.

A pair of channel members 24 are secured to the hous-v ing side walls 16and 1 8' near their front edges. The channel members 24"extend the fullheight of the hous sides exposed inwardly across the housing'.

The lift platform is raised and lowered 34. The shaft 34 is disposednear the bottom of the housing structure and is journaled within spacedbearing plates 36 and 3S. The bearing plate 38 extends across the frontface of the housing 12 and also serves as a structural brace for thehousing structure.

A similar bearing plate and shaft assembly is disposed at the top ofhousing 12. Such assembly includes spaced bearing plates 40 and 42having a shaft 44 rotatably journaled therein. The bearing plate 42extends across the front face of the housing structure 12 and serves toframe the opening in the housing and to provide a further structuralcross support.

A sprocket wheel 46 is mounted on the driven shaft 34 and a sprocketwheel 48 is mounted on the other shaft 44. An endless chain 50 isengaged with both sprocket wheels 46 and 48 and serves as the drivemeans for the lift platform S2.

The lift platform S2 includes a mounting plate 54 which serves as asupporting back wall. The mounting plate 54 is part of the lift carriage56 which carries a short run gravity conveyor structure 58.

The lift carriage 56 includes horizontally disposed arms 60 and 62 whichextend from the face of the mounting plate S4 and are supported bybraces 64 and 66 secured to brackets 68 and 70 on the mounting plate.The arm members 60 and 62 are disposed in parallel spaced relation toeach other inboard of the side edges of the mounting plate 54. They aresecured together by a cross brace The gravity conveyor 58 includes apair of parallel spaced wheeled tracks 74 and 76 which are mounted onthe lift carriage 56 in a horizontally inclined disposition. Theconveyor structure includes the track sections or rails 74 and 76 whicheach have a plurality of wheels 78 r0- tatably mounted thereon. Sideguide rails 80 and 82 are secured to the wheeled rails.

The conveyor tracks or rails 74 and 76 are secured to a tubular crossmember 84. Y A shaft 86 extends through the tubular member 84 and isiournaled in lugs 88 and 90 secured to arm 60 of the lift carriage. Thismakes the conveyor structure 58 pivotal on the lift carriage. The otherend of the conveyor structure 58 rests on supports 92 and 94 provided onarm 62 of the lift carriage.

The mounting plate S4 of the lift carriage structure is received forguided vertical travel within the open face of the housing 12. Themounting plate is engaged to the endless drive chain 50 by suitablehoist connectors 96 and 98. The upper edge of the mounting plate servesas an upper travel limiting stop upon engagement with the sprocket wheelshaft 44. The plate is cut out at 100 to permit lower travel prior tostop engagement with the other sprocket wheel shaft 34. l

. The mounting plate 54 is of sutiicient width to have its side edgesreceived within the channel members 24 and within the guide meansmounted therein. Such side edges thus serve as guide rails for the liftcarriage member.

Channel members 24 are of sufficient size to receive lengths of Wheeledconveyor track 102, 104 and 106 therein. The conveyor tracks are mountedon the side anges 108 and 110, and the back web 112, of the channelmembers. They are disposed in parallel spaced relation to each other andare of sufficient length to extend the full height of the channelmembers.

Each of the wheeled conveyor tracks 102, 104 and 106' are of the sameconstruction. Such track members are commonly known and are readilyobtainable. The track members each include a channel shaped structuralrail having a plurality of wheels 116 mounted between 1111;

side flanges 118 and 120 thereof. The web 122 of the rail isperiodically slotted to expose the wheels therethrough. The wheels 116are mounted 0n bolt shafts 124 which extend through the rail anges 118and 120. Spacers 126 center the wheels between the side flanges and anut 123 is threaded on the exposed end of the bolt shaft to complete theWheel assembly.

The rail members of the wheeled conveyor tracks 102, 104 and 106 havethe side walls 118 and 120 formed into the open face, near their ends.This provides strengthening ribs for the rail members. .It also providesa bearing surface for a bolt head which can be used to secure the guiderail members 102, 104, and 106 to the channel member. This is a commonlyknown means of attachment for this type of wheeled conveyor track andtherefore has not been illustrated.

The load bearing surfaces of the wheels 116, of tracks 102 and 104, areon opposite sides of the guide edge of the mounting plate 54, asreceived therebetween. Accordingly, the mounting plate 54 is engagedwith several wheels 116 of each of the guide tracks. Such engagementimposes a radial load on the wheels 116 but does not subject the wheelsto any end thrust load. Any movement of the mounting plate 54 in its ownplane, that is normal to the wheels of guides 102 and 104, is taken bythe Wheels 116 of guide track 106.

The load bearing surfaces of the wheels of guide tracks 106 are disposedfor end face engagement with the mounting plate 54. Accordingly themounting plate is restrained against lateral movement in its own plane.The wheels of rails 106 thus are disposed to take the thrust loading ofthe lift platform but to receive such load radially of the wheels 116thereof.

The lift platform may be signalled for a certain vertical travel. Alimit stop switch actuator 11S is mounted on the lift carriage 56. Suchactuator is intended to engage a limit switch connected to the drivemotor 26. The limit switch might be mounted on a table or the edge of astorage bin.

Operation The guide rail and lift platform structure shown issemi-portable in nature. It may be moved from one location to another. Aparticularly good use for such a device is in the loading and unloadingof heavy dies on and off of work tables, or the like.

The housing 12 and the structure thereof is located beside the die-worktable. A heavy die is disposed upon the conveyor section 58 of the liftplatform structure. The die is prevented from running oft the conveyorrails 74 and 76 by a suitable stop at their lower end.

The drive motor 26 is energized to raise the lift platform 52, via thechain drive connection thereto.

At the lift carriage 56 is actuated the mounting plate 54 is guided overthe many wheels 116 of the track sections 102, 104 and 106. The tracksections 102 and 104 are engaged with both side edges of the mountingplate. Accordingly there are a plurality of wheels to take the load ofthe extended carir-age. Similarly, the wheels of -track sections 106, inthe spaced guide channels 24, are engaged with both side end faces ofthe mounting plate 54 to take any load force due to eccentric loading onthe carriage. The mounting plate is of suicient height to be inengagement with several of the different wheels 116 at the same time.Accordingly the load of the carriage is distributed between thedifferent wheels.

The lift carriage moves freely within the guiding track sections 102,104 and 106 at each side thereof. The wheels 116 are of sufficientlylight construction to have a low inertia factor and can be readilyrotated into service. Such light construction is permissible due to theload distribution between the different wheels and the fact that theyare not continuously in service.

None of the wheels of the different guide track sections 102, 104 and106 are subjected to any end loading. The side and end face engagingdisposition of the Wheels enables each set of wheels to cooperate witheach other set to receive all bearing loads radially of the wheels.

The close spaced alignment of the side guide tracks 102 and 104 may beadjusted by shimming the track sections relative to the side walls ofthe housing channel member. The end face engaging tracks 106 may besimilarly adjusted and set.

Any injury to the guide rails, or damage to any of the wheels, isreadily corrected. Whole new sections of guide track may be replaced, orindividual wheel assemblies may be changed with little effort.

When the lift carriage 56 is signalled as having reached the requiredvertical height, as by the limit switch actuator 118, the drive motor 26is automatically inactivated. The tiltable conveyor section 58 may thenbe pivoted to raise its lower end higher than the other end Iand causethe die to move olf the conveyor bed and onto the work table. Thistilting operation may be by power operated means, if desired, but suchmeans are not shown here since they are quite well known and form noparticular part of this invention.

This structure is used in the reverse order to that described, inunloading work from a table area, storage bin, or the like.

While a preferred embodiment of this invention has been described itwill be understood that other modications and improvements may be madethereto. Such of these modications and improvements as incorporate theprinciples of this invention are to be considered as included in thehereinafter appended claim unless these claim by their languageexpressly state otherwise.

I claim:

A guide structure for -a lift platform comprising: a supporting channelmember having a web and a pair of flanges, channel-shaped rail meansmounted on said web and on each of said flanges, spaced wheelsprotruding through said rail means and mounted on said rail meansthroughout the extent thereof, each wheel being rotatable about an axisparallel to the portion of said channel member on which its rail ismounted, and an elongated plate member ixedly attached to said liftplatform, said plate member having three plane surfaces formed thereonfor engagement with said wheels, each of said surfaces beingsimultaneously engageable with no less than four of said wheelsthroughout the travel of said lift platform so as to limit its movementtoward any portion of said channel member.

References Cited in the le of this patent UNITED STATES PATENTS1,713,165 Bridge May 14, 1929 2,561,163 Wolters July 17, 1951 2,635,771Black Apr. 21, 1953 2,786,578 De Graaf Mar. 25, 1957

